In recent years there has been an increase in interest in the utilization of thermoplastic resins to reduce the processing cost of fiber-reinforced composites. Thermoplastic matrices offer the possibility of lessening the fabrication costs of advanced structures thereby making them cost competitive. The cost reductions are possible because faster and lower cost manufacturing procedures can be employed.
Since such resins must be processed in the melt under conditions where considerable flow is required, processing temperatures must, unfortunately, be considerably higher than ultimate use temperatures. This limitation presents a serious problem when the thermoplastic resins are considered for use in higher temperature environments. Reactive plasticizers provide a promising solution to this problem.
Reactive plasticizers lower the effective softening point of the thermoplastic resin during processing and then, during a final curing step, they react to form a crosslinked resin. Raising the softening temperature of the mixture to a temperature above the softening point of the neat thermoplastic can result if the molecular structure of the system is appropriately tailored.
It is an object of the present invention, therefore, to provide new and improved reactive plasticizers for use in the fabrication of heterocyclic thermoplastic resins.
Another object of the invention is to provide bis-ethynyl quinoxaline compositions.
A further object of the invention is to provide a method for synthesizing bis-ethynyl quinoxaline compositions.
Still another object of the invention is to provide a mixture of a polyphenyl quinoxaline thermoplastic and a plasticizer, the cured mixture having a higher softening temperature than the thermoplastic per se.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.